June 4, 2009

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

New Webcam menu makes lava views safely available

Lava in Kīlauea's summit vent creates a nighttime glow that can be safely observed from the Jaggar Museum overlook in Hawai'i Volcanoes National Park or on the HVO Webcam. Inset image shows the lava surface, which was moving from top center to lower left at the time it was taken.

The HVO Web site was recently revamped to make access to our increasing number of Webcams easier for viewers and the HVO staff who post Webcam images. All HVO Webcams are now linked through a single menu at http://hvo.wr.usgs.gov/cams/.

The menu lists our five Webcams showing Moku`aweoweo, Mauna Loa summit caldera, the TEB vent and lava tube system on Kīlauea's east rift zone, Pu`u `Ō `ō crater, and two views of the Halema`uma`u vent—one from HVO and another from the rim of Halema`uma`u crater immediately above the new vent.

Webcams allow us to make critical measurements with relatively little risk. The Webcams can work in rain, wind, very high concentrations of sulfur dioxide, and even moderate amounts of ash blasted from the vent. They can be in areas where access is restricted for safety reasons. Webcams can be where people should not.

Two of our Webcams have shown active lava in recent days. On Tuesday night, the TEB Webcam caught active flows near the top of the abandoned Royal Gardens subdivision. As an added treat, the Webcam also caught lights from a cruise ship passing the Kalapana shoreline in the late evening getting good views of the active flows and the Waikupanaha ocean entry.

The Webcams that chronicle developments below the floor of Halema`uma`u Crater have recorded lots of glow since early May. In fact, the recent glow has been the brightest since October 2008. The brightness of the glow is due to molten lava circulating in a narrow conduit about 100 m below the crater floor and about 180 m below the crater rim.

The Webcam located on the rim of Halema`uma`u was recently repositioned to look directly into the vent for views of the circulating lava when clear enough. The wispiness of the gas plume and the relative shallowness of the molten lava have allowed some good views recently. The vent is masked by sunlit fume during the day and is overexposed at night so the best times to look at Webcam views of lava are at dusk and dawn.

The unwavering Webcam views will allow us to better monitor the rise and fall of the lava within the vent. HVO geologists have also recorded video of the lava surface that shows some fascinating movements (http://hvo.wr.usgs.gov/multimedia/images.html). The lava emerges from the right side of the Webcam view and flows left across the opening. The flowing lava surface looks chaotic with lots of splashing and bursting bubbles—activity that produces the tephra that is carried aloft by the hot, rising gas and deposited on the rim.

Two recent Volcano Watches have discussed reasons for lava circulation using a lava lamp analogy. Magma must be convecting with the conduit, like the "goo" in a lava lamp, bringing hot, bubble-rich lava to the surface while allowing cooler, bubble-poor lava to sink.

Looking at lava within the Halema`uma`u vent conduit is like watching a lava lamp from above through a hole in the top, all the goo colored orange, and blobs being gas bubbles that burst when they get to the top.

Views from the Halema`uma`u Webcam should allow us to test our ideas about what precedes brown plumes and explosive eruptions. Do rocks fall from vent walls into the molten circulating lava trigger a vigorous gas release which could carry even more spatter and rock dust out of the vent. Or are the brown plumes and more energetic explosive eruptions initiated by a big slug of gas coming up the conduit.

For safety reasons, Hawai`i Volcanoes National Park restricts access to the entire caldera including Crater Rim Drive from Jaggar Museum south to the Chain of Craters Road intersection. Thanks to the HVO Webcams, we can all see what's happening from much safer vantage points.

Kīlauea Activity Update

A deflation/inflation (DI) event at the summit of Kīlauea last weekend disrupted the supply of lava through the tube system and caused the Waikupanaha and Kupapa`u ocean entries to shut down. Both entries had resumed by mid-week, accompanied by breakouts near the top of Royal Gardens subdivision and just inland from Kupapa`u.

At Kīlauea's summit, the vent within Halema`uma`u Crater continues to emit elevated amounts of sulfur dioxide gas, resulting in high concentrations of sulfur dioxide downwind. Vigorously upwelling lava within the vent below the crater floor produced bright glow at night, loud gas-rushing noises, and the emission of juvenile ash during the past week.

One earthquake beneath Hawai`i Island was reported felt this past week. A magnitude-3.4 earthquake occurred at 3:55 p.m., H.s.t, on Saturday, May 30, 2009, and was located 9 km (6 miles) southwest of Kīlauea Summit at a depth of 26 km (16 miles).